ACTINIA FEOM THE MERGUI AECHIPELAGO. 255 



The combinations of lenses mentioned below refer to Zeiss's system. 



Fig. 1. Side view of a preserved specimen. Natural size. 



2. Portion of same. X 2 diameters. 



3. Portion of base, seen from below. X 2 diameters. 



4. Inner view of part of the body, showing one gonidial groove (oesopha- 



geal groove) and a secondary septum. Natural size. 



5. Transverse section through one twelfth of the body below the oesophagus. 



2 



a*0' 3 



6. Transverse section through a mesentery. ^F[q- 



7. Portion of a longitudinal section through the capitulum, showing the 



endoderm crowded with zooxanthella?, the feeble endodermal circular 



2 



muscle, and the nature of the mesogloea. — . 



A 



8. Portion of teased tube, with an alcyonarian and a sponge-spicule. 



2 



B ' 2 



9. Isolated nematocyst, partially exploded. — . 



Plate XX. 

 Hormathia Andcrsoni, sp. n. 



a. Acontia. b. Mesenteric filaments (craspeda). d. Unicellular glands. 

 eh. Ectoderm, en. Endoderm. g. Reproductive organs (gonads), h. Me- 

 senteries ; I.— IV. indicate the rank of the pairs of mesenteries, i. Oral disk. 

 h. Body-wall. I. Pedal disk. Ip. Eip of mouth, m. Muscles, me. Me- 

 sogloea (mesoderm), ml. Longitudinal muscles of mesenteries, mr. Radial 

 muscles of oral disk. ms. Circular muscle, n. Nematocysts. rh. Directive 

 mesenteries, s. (Esophagus, sg. Grains of sand forming investment to the 

 ectoderm, t. Tentacles ; 1 primary. 2 secondary. 



The combinations of lenses mentioned below refer to Zeiss's system. 



Fig. 1. View from above of specimen a. x 2 diameters. 



2. Side view of specimen b. x 2 diameters. 



3. Vertical section through specimen c. x 4 diameters. 



2 



4. Transverse section through upper portion of body-wall. . 



5. Transverse section through the oesophagus. — — . 



a*o 



6. Horizontal section through the tertiary mesentery indicated by an 



3 



asterisk (*) in fig. 5. j. 



2 



7. Nematocysts from a tentacle. — . 



8. Nematocvsts from an acontium. 



F 



9. Transverse section through an acontium. 



2 

 D' 



9 



10. Vertical section through horizontal portion of circular muscle. 







